JP2010206994A - Motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor which is equipped with a cooling structure that can suppress deviated flow of a fluid flowing in a cooling space. <P>SOLUTION: The motor 11 is equipped with a cylindrical case 13 which houses a rotor 17 and a stator 19. The case 13 has the cooling space 50, which is formed along substantially the entire circumferential direction and allows the fluid to circulate. A plurality of grooves 27 (irregularities) are formed along substantially the entire circumferential direction at the outer face of an inner cylinder 21 which faces the cooling space 50. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electric motor.

  In general, electric motors are used for industrial machines such as construction machines, agricultural machines, machine tools, and self-propelled vehicles such as automobiles. In such an industrial machine, since a large current is supplied to the electric motor, the electric motor has a cooling structure for suppressing heat generation at that time. For example, Patent Literature 1 discloses a technique related to a cooling structure that circulates cooling water along the circumferential direction around an outer peripheral portion of a case.

JP 2008-259326 A

  In the electric motor described in Patent Document 1, the cooling space for circulating the cooling water is formed over the entire circumferential direction in the outer peripheral portion of the case, so that a constant cooling effect can be obtained, but the motor specifications are increased in output. Accordingly, further improvement of the cooling effect is desired.

  Therefore, the present invention has been made in view of such a point, and an object thereof is to provide an electric motor including a cooling structure capable of improving a cooling effect.

  The electric motor of the present invention includes a cylindrical case (13) that houses the rotor (17) and the stator (19). The case (13) has a cooling space (50) that is formed over substantially the entire circumference in the inside thereof, and is capable of circulating a fluid. The case (13) faces the cooling space (50). Concave and convex portions (27) are formed on the surface.

  In this structure, since it has the uneven | corrugated | grooved part (27) provided in the surface of the said case (13) facing the cooling space (50), the fluid and case (13) which flow through the cooling space (50) The contact area with the surface can be increased. Thereby, since the heat transfer area from a fluid to a case (13) increases, a cooling effect can be improved.

  Further, when the uneven portion (27) is a groove, the fluid easily flows along the groove. Thereby, since heat exchange between the fluid and the case (13) is promoted, the cooling effect can be further improved.

  Moreover, when the said uneven | corrugated | grooved part (27) is formed in the surface of the case (13) facing the cooling space (50) over substantially the whole circumferential direction, contact with the surface of the fluid and the case (13) The area can be increased over substantially the entire circumferential direction of the cooling space (50). As a result, the heat transfer area from the fluid to the case (13) can be further increased, and a cooling effect can be obtained uniformly over substantially the entire circumferential direction of the cooling space (50).

  Further, in the case (13), the rotor (17) and the stator (19) are accommodated radially inward from the cooling space (50), and the uneven portion (27) Of the surface of the case (13) facing the cooling space (50), it is preferably provided on the surface located on the radially inner side of the case (13).

  In this configuration, the arrangement position of the concavo-convex portion (27) is closer to the rotor (17) and the stator (19), which are main heat generation sources when the electric motor is driven, so that the cooling efficiency is further improved. Can be made.

  The case (13) is disposed on the outer side of the inner cylindrical portion (21) and the cylindrical inner cylindrical portion (21) that houses the rotor (17) and the stator (19), and the inner cylindrical portion. A cylindrical outer tube portion (23) that is fixed to (21) and forms the cooling space (50) between the inner tube portion (21) and the concavo-convex portion (27), You may be provided in at least one of the outer surface of the said inner cylinder part (21), and the inner surface of the said outer cylinder part (23).

  In this configuration, the case (13) has a cooling space (50) between the inner cylindrical portion (21) and the cylindrical inner cylindrical portion (21) that accommodates the rotor (17) and the stator (19). And a cylindrical outer tube portion (23) that forms a concave-convex portion (27), and the concavo-convex portion (27) is substantially the entire circumferential direction on at least one of the outer surface of the inner tube portion (21) and the inner surface of the outer tube portion (23) It is provided over. Thereby, since the heat transfer area from a fluid to an inner cylinder part (21) or an outer cylinder part (23) increases, a cooling effect can be improved.

  When the concave and convex portion (27) is provided on the outer surface of the inner cylinder portion (21), the concave and convex portion is formed on the rotor (17) and the stator (19) which are main heat generation sources when the electric motor is driven. The arrangement position of (27) can be made closer. Thereby, cooling efficiency can be improved more.

  When the outer cylinder part (23) is configured separately from the inner cylinder part (21), the attachment position with respect to the inner cylinder part (21) can be arbitrarily selected in the circumferential direction. Moreover, since these are separate bodies, after an uneven | corrugated | grooved part (27) etc. are formed in advance in an outer cylinder part (23) or an inner cylinder part (21), an outer cylinder part (23) is made into an inner cylinder part (21). Therefore, it is easy to process the uneven portion (27). In particular, when the concavo-convex portion (27) is provided on the outer surface of the inner cylinder portion (21), further processing is performed compared to the case where the concavo-convex portion (27) is formed on the inner surface of the outer cylinder portion (23). It becomes easy.

  When the fluid is an insulating oil, it is possible to reduce the risk of electric leakage as compared with the case where a fluid such as water is used.

  When an electric motor is used for hydraulic equipment and the insulating oil is hydraulic oil for the hydraulic equipment, part of the hydraulic oil can be used as a fluid flowing into the cooling space (50). Thereby, the piping structure, tank structure, etc. of hydraulic equipment can be simplified.

  As described above, according to the present invention, since the concave and convex portions are provided on the surface of the case facing the cooling space, the contact area between the fluid flowing in the cooling space and the surface of the case is reduced. Can be increased. Thereby, since the heat transfer area from a fluid to a case increases, a cooling effect can be improved.

It is sectional drawing which cut | disconnected the electric motor of embodiment of this invention to the axial direction of the shaft. It is sectional drawing which showed the inner cylinder part, outer cylinder part, and stator of embodiment of FIG. 1, and cut | disconnected these in the axial direction. (A) is a perspective view which shows the structure of the inner cylinder part when the electric motor of embodiment of FIG. 1 is seen from an entrance side, (b) is the side which opposes this electric motor to a radial direction with respect to an entrance. It is a perspective view which shows the structure of the inner cylinder part when it sees from. It is a perspective view which shows structures, such as a case and a stator, in the electric motor of embodiment of FIG. It is a perspective view which shows the shape of the space for cooling in the electric motor of embodiment of FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the electric motor 11 according to this embodiment includes a case 13, a shaft 15 that is rotatably supported by the case 13 along the axial direction of the case 13, and a circle attached to the shaft 15. A columnar rotor 17 and a stator 19 facing the rotor 17 are provided.

  As shown in FIGS. 1 and 2, the case 13 includes a cylindrical inner cylinder portion 21, a cylindrical outer cylinder portion 23 that covers the outer surface of the inner cylinder portion 21, and both axial sides of the inner cylinder portion 21. The disk part 29 and the disk part 31 which block | close each opening part are included. The inner cylinder part 21, the outer cylinder part 23, the disk part 29, and the disk part 31 are manufactured separately and then integrated.

  The disc part 29 is fitted in the opening part of the inner cylinder part 21 on the first direction D1 side, and is fixed to the end part of the inner cylinder part 21 by a bolt (not shown). A concave portion in which one end portion of the shaft 15 is disposed is formed on the inner surface of the disk portion 29. A bearing 33 is interposed between the inner peripheral surface of the recess and the outer peripheral surface of the shaft 15.

  In addition to the form in which one end portion of the shaft 15 is disposed in the recess as shown in FIG. 1, for example, a not-shown through hole through which the shaft 15 can be inserted is provided in the disk portion 29, and the shaft 15 The form by which the one end part was penetrated may be sufficient. In the case of this form, it is possible to output rotational motion at both ends of the shaft 15. In the case of this embodiment, one end of the shaft 15 is set as the input side of the rotary motion, and the other end is set as the output side of the rotary motion, so that the input side assists the rotary motion on the output side. You can also.

  The disc part 31 is fitted in the opening part of the inner cylinder part 21 on the second direction D2 side, and is fixed to the end part of the inner cylinder part 21 by a bolt (not shown). A through hole through which the other end of the shaft 15 is inserted is formed at the center of the disk portion 31. A bearing 35 is interposed between the inner peripheral surface of the through hole and the outer peripheral surface of the shaft 15. In this way, the shaft 15 is rotatably supported by the disk portions 29 and 31. Note that the end portion of the shaft 15 on the second direction D2 side and the disk portion 31 are attached to the body of an industrial machine such as a hydraulic machine.

  A stator 19 is disposed on the inner surface of the inner cylinder portion 21 along the circumferential direction. The stator 19 is disposed opposite the outer peripheral surface of the rotor 17 with a predetermined gap. The stator 19 has a core 19a attached so as to be in thermal contact with the inner surface of the inner cylinder portion 21, and a winding 19b wound around the core 19a.

  As shown in FIGS. 3A and 3B, the inner cylinder part 21 includes a body part 40 that forms a cooling space 50 that serves as a fluid flow path together with the outer cylinder part 23, and a second part of the body part 40. And a flange portion 41 provided at the end on the direction D2 side. The flange portion 41 includes an insertion portion 43 having a through hole 43a and a wiring portion 45 having a through hole 45a (see FIG. 2) through which a conducting wire for supplying electric power to the electric motor 11 is inserted. As shown in FIG. 4, the inner cylinder portion 21 is configured such that the bolt 44 is inserted into the through hole in a state where the screw holes of the nut portion 46 provided on the outer surface of the outer cylinder portion 23 and the through holes 43 a of the insertion portion 43 are aligned. It is connected to the outer cylinder part 23 by being inserted into 43a and screwed into the screw hole of the nut part 46. A flat plate 47 that closes the opening of the wiring portion 45 is screwed to the side portion of the wiring portion 45.

  As shown in FIGS. 3A and 3B, the body portion 40 includes an outer edge portion 37 provided at an end portion on the first direction D1 side and an outer edge portion provided on an end portion on the second direction D2 side. 39 and a partition 81 provided between the outer edge portions 37 and 39. The outer edge portion 37, the outer edge portion 39, and the partition 81 have opposing surfaces 37a, 39a, 81a that face the inner surface of the outer cylinder portion 23 along the circumferential direction, respectively. In the present embodiment, the outer diameters of these facing surfaces 37a, 39a, 81a are adjusted to be approximately the same. However, the outer diameters of these facing surfaces 37a, 39a, 81a are not necessarily the same. That is, the space between the facing surface 37a and the inner surface of the outer cylinder portion 23 is sealed by an O-ring disposed in a lower groove 49 described later, and the space between the facing surface 39a and the inner surface of the outer tube portion 23 is on the upper side. What is necessary is just to be sealed to some extent by the partition 81 between the 1st cooling part 51 and the 2nd cooling part 52 which are sealed by the O-ring arrange | positioned in the groove | channel 49, and are mentioned later. If these conditions are satisfied, for example, the outer diameters of the opposing surfaces 37a, 39a, 81a may be different, and the inner surface of the outer cylinder portion 23 may be curved or inclined with respect to the axial direction.

  As shown in FIGS. 2 and 4, the outer cylinder part 23 is a cylindrical member that covers the outer surface of the body part 40 of the inner cylinder part 21. The outer cylinder portion 23 covers the outer surface of the body portion 40 and is disposed at a predetermined interval with respect to the outer surface, thereby forming a cooling space 50 through which fluid can flow with the body portion 40. ing. A fluid inlet 60 and an outlet 62 communicating with the cooling space 50 are provided on the outer surface of the outer cylinder portion 23.

  A first concave portion 91 having an outer diameter smaller than these is formed along the circumferential direction between the outer edge portion 37 and the partition 81, and the outer edge portion 39 and the partition 81 have an outer periphery smaller than these. A second recess 92 having a small diameter is formed along the circumferential direction. Thereby, when the outer cylinder part 23 is arranged so as to cover the outer surface of the inner cylinder part 21, the inner surface of the outer cylinder part 23 faces the outer edges 37, 39 and the opposing surfaces 37a, 39a, 81a of the partition 81. Thus, a space is formed between the first recess 91 and the second recess 92 between the inner surface of the outer cylinder portion 23. These spaces become the first cooling part 51 and the second cooling part 52 that constitute a part of the cooling space 50. Thus, the cooling space 50 is divided into the first cooling part 51 and the second cooling part 52 in the axial direction.

  Further, an O-ring groove 49 is formed along the circumferential direction between the outer edge portion 37 and the first recessed portion 91, and between the outer edge portion 39 and the second recessed portion 92 in the circumferential direction. Along with this, an O-ring groove 49 is formed. O-rings (not shown) are arranged in these grooves 49, respectively. Thereby, the watertightness between the outer cylinder part 23 and the outer edge parts 37 and 39 of the inner cylinder part 21 is improved.

  A plurality of grooves 27 (five grooves 27 in the present embodiment) that are recessed inward in the radial direction are formed in the first recess 91 and the second recess 92, respectively, along the circumferential direction. The grooves 27 are substantially parallel to each other and are formed over substantially the entire circumferential direction.

  The first cooling part 51 communicates in the radially outer space while the radially inner space is partitioned into a plurality of spaces by the annular protrusions that form the wall surfaces of the grooves 27. . Similarly to the first cooling part 51, the second cooling part 52 has a radial inner space partitioned into a plurality of radial inner spaces by an annular protrusion constituting the wall surface of each groove 27. The space on the outer side of is communicated in the axial direction. By adopting such a configuration, in the first cooling part 51 and the second cooling part 52, the contact area between the fluid and the outer surface of the inner cylinder part 21 is increased on the radially inner side, while the radial direction is increased. It is possible to suppress an increase in fluid flow resistance on the outer side. Thereby, the cooling efficiency can be improved and the pressure loss when the fluid flows can be reduced.

  As shown in FIG. 3B, the partition 81 has an opening 71 located in a region in a predetermined range in the circumferential direction on the side facing the inlet 60 in the radial direction. The opening 71 is a recess recessed inward in the radial direction formed by cutting a part of the partition 81. The opening 71 constitutes the first junction 61 together with the inner surface of the outer cylinder 23 (see FIG. 5).

  The first merging portion 61 is a part of the cooling space 50, and is located in a region in a predetermined range in the circumferential direction on the side facing the inlet 60 in the radial direction, and the first cooling portion 51 and the second cooling portion. The part 52 is communicated.

  Here, in the present embodiment, the “region in a predetermined range in the circumferential direction on the side facing the inlet 60 in the radial direction” specifically means the following. First, the axial position of this region is between the first cooling part 51 and the second cooling part 52. Next, the position in the circumferential direction of this region can be exemplified in several forms as follows. As an example of the position in the circumferential direction, when the cooling space 50 is viewed in plan (when the cooling space 50 is viewed in the axial direction of the shaft 15), it is on the axis of the cylindrical first cooling unit 51. An area having a predetermined width in the circumferential direction from the opposite position is included. This embodiment is this type.

  In addition, as another example of the circumferential position, the opposed position may not necessarily be included, and two regions separated from each other at substantially equal distances from the opposed position to one side and the other side in the circumferential direction. Is included. Further, as another example of the position in the circumferential direction, a region where the above two examples are combined can be cited.

  Further, from the viewpoint of enhancing the effect of suppressing the drift of the fluid in the first cooling section 51, the circumferential position of the first merging section 61 is substantially a line with respect to the straight line connecting the center of the inlet 60 and the facing position. It is preferable that the shape is symmetrical. Moreover, it is more preferable that the range where the 1st confluence | merging part 61 is extended in the one side and the other side of the circumferential direction is contained in the area | region of +/- 45 degrees from the said opposing position from a viewpoint of drift suppression.

  In addition, the meaning content regarding the arrangement | positioning area | region of the above-mentioned 1st junction part 61 is the same also about the 2nd junction part mentioned later. That is, the “region of a predetermined range in the circumferential direction on the side facing the inlet 60 in the radial direction” in the above description of the first merging portion 61 is referred to as “first merging portion 61 in the case of the second merging portion 62. On the other hand, it is read as “a region in a predetermined range in the circumferential direction on the opposite side in the radial direction”.

  As shown in FIGS. 3A, 4, and 5, the cooling space 50 is a second merge located in a region in a predetermined range in the circumferential direction on the side facing the first merge portion 61 in the radial direction. A portion 62 is provided. This 2nd junction part 62 functions as the exit 62 for discharging | emitting a fluid outside in this embodiment. The fluid flowing separately in the second cooling section 52 on one side and the other side in the circumferential direction merges at the outlet 62. The outlet 62 is located on the same side in the circumferential direction as the inlet 60 and is aligned with the inlet 60 in the axial direction.

  Further, as shown in FIG. 3A, the partition 81 has a circumferential position close to the inlet 60 and has an opening 25 a at a position between the inlet 60 and the outlet 62. The opening 25a is a recess that is formed by cutting a part of the partition 81 and is recessed inward in the radial direction. This opening 25a constitutes the communication part 25 for venting air with the inner surface of the outer cylinder part 23 (refer FIG. 5). The communication part 25 is a part of the cooling space 50 and communicates the first cooling part 51 and the second cooling part 52.

  The opening length in the circumferential direction of the opening 71 is not particularly limited as long as it is appropriately set according to the viscosity of the fluid to be used, the supply amount of the fluid, and the like, but is set to be at least larger than the opening 25a. Is done. That is, the opening area of the first merging portion 61 is applied to the fluid so that the fluid flowing through one side and the other side in the circumferential direction of the first cooling portion 51 merges and smoothly flows to the second cooling portion 52 side. It is set in consideration of resistance. On the other hand, the opening area of the communication part 25 can move the air staying in the first cooling part 51 to the second cooling part 52 side, and the fluid supplied from the inlet 60 passes through the communication part 25 to the first. It is preferable to set a value sufficiently smaller than that of the first merging portion 61 to such an extent that the flow to the second cooling portion 52 side can be suppressed as much as possible.

  Water can be used as the fluid, but the risk of electrical leakage can be reduced by using, for example, insulating oil. As the insulating oil, when the electric motor 11 is used in a hydraulic device, it is preferably a hydraulic oil for the hydraulic device.

  Next, operation | movement of the electric motor 11 of this embodiment is demonstrated. First, when electric power is supplied to the motor 11, a magnetic force is generated between the rotor 17 and the stator 19 and the shaft 15 rotates. As the electric motor 11 is driven, the rotor 17 and the stator 19 mainly generate heat. In order to suppress the temperature rise of the electric motor 11 due to this heat generation, for example, hydraulic oil as a cooling fluid is supplied to the cooling space 50 through the inlet 60.

  The fluid supplied from the inlet 60 branches into one side and the other side in the circumferential direction of the first cooling unit 51 and flows through the first cooling unit 51. In the present embodiment, since the first merging portion 61 is provided at the facing position, the ratio of the fluid that branches and flows to one side and the other side in the circumferential direction of the first cooling portion 51 becomes substantially equal.

  These branched fluids merge at the first merge unit 61 and flow into the second cooling unit 52. The fluid that has been branched in this way is once merged and then flowed into the second cooling unit 52, so that the uniformly mixed fluid can be sent to the second cooling unit 52 when passing through the first merged unit 61. it can. Thereby, the dispersion | variation in the cooling effect in the 2nd cooling part 52 can be reduced.

  The fluid that has flowed into the second cooling unit 52 branches again to one side and the other side in the circumferential direction of the second cooling unit 52 and flows through the second cooling unit 52. These branched fluids join again at the second joining portion (exit) 62 and are discharged from the exit 62 to the outside. Since the outlet 62 is provided in a region in a predetermined range in the circumferential direction on the side facing the first merging portion 61 in the radial direction, the outlet 62 branches to one side and the other side in the circumferential direction of the second cooling unit 52. The ratio of flowing fluid is almost even. The discharged fluid may be cooled and reused after being circulated for cooling.

  As described above, according to the present embodiment, since the uneven portion 27 is provided on the surface of the case 13 facing the cooling space 50, the fluid flowing in the cooling space 50 and the case 13 The contact area with the surface can be increased. Thereby, since the heat transfer area from the fluid to the case 13 increases, the cooling effect can be improved.

  Moreover, in this embodiment, since the uneven | corrugated | grooved part 27 is a groove | channel, it becomes easy to flow a fluid along this groove | channel. Thereby, since heat exchange between the fluid and the case 13 is promoted, the cooling effect can be further improved.

  In the present embodiment, since the uneven portion 27 is formed on the surface of the case 13 facing the cooling space 50 over substantially the entire circumferential direction, the contact area between the fluid and the surface of the case 13 is determined as the cooling space. It can be increased over substantially the entire 50 circumferential directions. As a result, the heat transfer area from the fluid to the case 13 can be further increased, and a cooling effect can be obtained evenly over substantially the entire circumferential direction of the cooling space 50.

  In the present embodiment, in the case 13, the rotor 17 and the stator 19 are accommodated in the radial direction with respect to the cooling space 50, and the uneven portion 27 is located in the cooling space 50. Of the surface of the case 13 facing the surface of the case 13, the surface of the case 13 is located on the inner side in the radial direction, and the rotor 17 and the stator 19, which are main heat sources when the motor is driven, The arrangement position is closer. Thereby, cooling efficiency can be improved more.

  In the present embodiment, since the uneven portion 27 is provided on the outer surface of the inner cylinder portion 21, the uneven portion 27 is arranged on the rotor 17 and the stator 19 which are main heat generation sources when the electric motor is driven. The installation position can be made closer. Thereby, cooling efficiency can be improved more.

  Moreover, in this embodiment, since the said outer cylinder part 23 is comprised separately from the said inner cylinder part 21, the attachment position with respect to the inner cylinder part 21 can be arbitrarily selected in the circumferential direction. Moreover, since these are separate bodies, the outer cylindrical portion 23 can be fixed to the inner cylindrical portion 21 after the concave and convex portions 27 and the like are formed in the outer cylindrical portion 23 or the inner cylindrical portion 21 in advance. 27 becomes easy. In particular, when the concavo-convex portion 27 is provided on the outer surface of the inner cylinder portion 21 as in the present embodiment, the processing is further facilitated as compared with the case where the concavo-convex portion 27 is formed on the inner surface of the outer cylinder portion 23. Become.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the configuration in which the grooves as the concavo-convex portions are continuous in the circumferential direction on the outer surface of the inner cylindrical portion has been described as an example, but the present invention is not limited to this. As the concavo-convex portion, for example, a spiral groove, a plurality of grooves formed along the axial direction, a plurality of protrusions, a plurality of dimples, and the like may be formed on the surface of the case facing the cooling space.

  Moreover, in the said embodiment, although the uneven | corrugated | grooved part was demonstrated and mentioned as an example in the form provided in the outer surface of the inner cylinder part, if the uneven | corrugated | grooved part is the surface of the case facing the space for cooling, for example, an outer cylinder part It may be another part such as the inner surface. For example, the uneven part may be provided on both the outer surface of the inner cylinder part and the inner surface of the outer cylinder part.

  Moreover, although the case where the space 50 for cooling was divided | segmented into two of the 1st cooling part and the 2nd cooling part was illustrated in the said embodiment, even if the space 50 for cooling is not divided | segmented as mentioned above, Moreover, it may be further subdivided than the above.

  Moreover, in the said embodiment, although the case where the inner cylinder part and outer cylinder part which form the space for cooling were separated was mentioned as an example, these inner cylinder parts and outer cylinder parts are not separate bodies. It may be an integral member.

DESCRIPTION OF SYMBOLS 11 Electric motor 13 Case 17 Rotor 19 Stator 21 Inner cylinder part 23 Outer cylinder part 27 Groove 50 Cooling space 51 1st cooling part 52 2nd cooling part 60 Inlet 61 1st junction part 62 Outlet (2nd junction part)
71 Opening 81 Partition

Claims (9)

An electric motor comprising a cylindrical case (13) for accommodating a rotor (17) and a stator (19),
The case (13) has a cooling space (50) that is formed over substantially the entire circumference in the inside thereof, and is capable of circulating a fluid. The case (13) faces the cooling space (50). An electric motor having an uneven portion (27) formed on the surface.   The electric motor according to claim 1, wherein the uneven portion is a groove.   3. The electric motor according to claim 1, wherein the concavo-convex portion (27) is formed on the surface of the case (13) facing the cooling space (50) over substantially the entire circumferential direction. In the case (13), the rotor (17) and the stator (19) are accommodated radially inward of the cooling space (50),
The said uneven | corrugated | grooved part (27) is provided in the surface located in the radial inside of the said case (13) among the surfaces of the said case (13) facing the said space for cooling (50). The electric motor in any one of -3. The case (13) is disposed on the outer side of the inner cylindrical portion (21) and the cylindrical inner cylindrical portion (21) that houses the rotor (17) and the stator (19), and the inner cylindrical portion. A cylindrical outer cylinder portion (23) fixed to (21) and forming the cooling space (50) between the inner cylinder portion (21),
The electric motor according to any one of claims 1 to 3, wherein the uneven portion (27) is provided on at least one of an outer surface of the inner tube portion (21) and an inner surface of the outer tube portion (23).   The electric motor according to claim 5, wherein the uneven portion (27) is provided on an outer surface of the inner tube portion (21).   The electric motor according to claim 5 or 6, wherein the outer tube portion (23) is formed separately from the inner tube portion (21).   The electric motor according to claim 1, wherein the fluid is an insulating oil. An electric motor used for hydraulic equipment,
The electric motor according to claim 8, wherein the insulating oil is hydraulic oil for the hydraulic device.

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